The invention relates generally to computer systems and networks, and deals more particularly with a file manager for files which are shared by heterogeneous clients that exhibit different communication protocols.
A local area network (LAN) was previously known which includes multiple homogeneous clients and a network server. For example, the clients on one network can all exhibit a network file system (NFS) protocol or can all exhibit a server message block (SMB) protocol. Each of the clients comprises a personal computer or workstation with an operating system such as an IBM DOS or AT&T UNIX operating system or IBM OS/2 operating system, and a network adapter card (such as a Token-ring or Ethernet adapter card) and a client program which interfaces the personal computer or workstation to the other clients and the network server. The network server also comprises a personal computer or workstation with an operating system such as IBM OS/2 operating system or a Novell Netware operating system, and a network adapter card and a network server program which interfaces the personal computer or workstation of the network server to the other clients and provides various services to the clients. For example, the network server manages a common storage disk, printer and modem. Thus, any of the clients can read from and write to a common directory and common files which are stored on the common storage disk, use the printer and communicate over the modem.
An IBM VM/ECF program executing in an IBM System/370 host computer was also previously known which provides services to multiple homogeneous clients exhibiting a Server-Requester Programming Interface (SRPI) protocol. In this system, each client is logically coupled to, assigned to and serviced by a different virtual machine within the host computer, and the virtual machine for each client manages a resource or resources dedicated to the client.
An IBM VM/NFS program executing in an IBM System/370 host computer was also previously known which provides services to multiple homogeneous clients exhibiting an NFS protocol. In this system, each client can communicate with one or more host computers to obtain services from the host computer. For example, each of the host computers provides a file manager common to all of the clients. The common file manager services NFS client requests by transforming the NFS protocol to a CMS protocol. However, the file manager supports only those NFS data formats which are compatible with CMS.
Another previously known Novell Netware 3.1 computer network comprises two local area networks, one supporting clients which all exhibit the NFS protocol and execute AT&T's Unix operating system, and the other supporting clients which all exhibit a Novell SPX protocol and execute DOS or OS/2 operating system. Alternately, the different clients can all reside in the same network. Each of the networks or the sole network in the alternate case is coupled to a common server which has a different protocol converter for each client protocol type, in the foregoing example, one for the NFS protocol clients, and the other for the SPX clients. Each of the protocol converters interprets the requests from the respective client types and performs the file system operation. While there is one file manager for all protocol converters and client types, there is a separate file name space for the names of files created by the clients of each protocol type. The file name spaces also include pointers from each file name in the name space to a storage location on a common disk. The file manager supports a request by a human network service administrator to link the file names in one file name space to the other file name space. Pursuant to such a request, the file manager will copy the names and associated pointers from the one name space to the other name space. After such linking, the clients associated with this other name space can read, change or delete the file names in this other name space and read from and write to the files which were linked from the one name space. Nevertheless, the clients associated with this other name space cannot access the one name space and probably not delete files which were linked from the one name space. Also, this system inlcudes a lock manager (or managers) which associates locks with file names within one name space only. Consequently, if the lock manager is called to place a lock on a file or file name (in one name space) that is the subject of a client request, the file name is not locked on the other name space so that clients associated with this other name space can simultaneously access the same file. The lock is only effective against clients of the same type or the client that made the request causing the lock to be established, and which use the same name space.
A general object of the present invention is to provide a system for true sharing of files between heterogeneous clients.
Another general object of the present invention is to provide a system of the foregoing type which includes a true lock manager.
Another object of the present invention is to provide a system of the foregoing type which also supports files which are dedicated to each client.